Sigma is said to be as the function that is adding in series of number. This sigma can be denoted by ∑ using the limit. Example: Let take the function as f(x). The sigma representation of the
function is to be added from 1 to n times is denoted as `sum_(x=1)^n` f(x) = f(1) + f(2) + f(3) --- f(n). In this article, we study about formula for sigma.